Not even sure where to start. I started encountering this issue after I updated my network driver.
I have an Asus G73JW laptop with Intel Centrino Ultimate-N 6300 AGN. Whenever I resume the laptop after being suspended or on standby the network card becomes unavailable. The laptop indicates that networks are available but it doesn't show the list of networks. As if the network card is completely missing. The only way to get the network connectivity back is to uninstall the network card using Windows Device Manager under Network Adapters then use "Scan for hardware changes." Windows goes through the hardware discovery and installing the driver. After connecting to my wireless network everything works great. Until the next time I resume the laptop.
This started happening after I updating the driver to version 22.214.171.124 dated 8/3/11. I've tried reverting to the previous version with the same results. This happens almost 9 out of 10 times.